1. Field of the Invention
The present invention relates to a slide plate and a rack guide that receive a rack bar of a rack and pinion type steering device, and particularly to a configuration for attaching the slide plate to a rack guide base body of the rack guide.
2. Description of Related Art
Conventionally, a rack and pinion type steering device is constituted to include a pinion which is rotated by a steering wheel, and a rack bar having rack teeth which mesh with the pinion so as to convert the rotation of the pinion into linear movement of the rack bar.
The pinion of the rack and pinion type steering device is rotatably supported by a casing via a bearing, and an outer peripheral surface of the rack bar having a circular arc shape on an opposite side to a rack tooth formed side is supported by a rack guide in the casing. The rack guide consists of a rack guide base body with a recessed portion of a circular arc shape formed at an end portion, and a slide plate of a curved shape formed so that its inner surface corresponds to the outer surface of the circular arc shape of the rack teeth of the rack bar, and is constituted by mounting the slide plate on the recessed portion of the rack guide base body. By coating the surface of the slide plate to be in contact with the rack bar with a material with a low friction coefficient such as polytetrafluoroethylene (PTFE), slidability of the rack bar is enhanced.
In order to fix the slide plate to the rack guide base body, JP-A-2002-2506 adopts a configuration in which a fitting hole portion is formed in a center of the recessed portion of the rack guide base body, a fitting projected portion which is fitted into the fitting hole portion is formed on the slide plate, and the fitting projected portion is press-fitted into the fitting hole portion, for example.
The fitting projected portion provided on the slide plate is formed by drawing, and therefore, is generally formed into a cylindrical shape. However, in the method in which the slide plate having the cylindrical fitting projected portion formed thereon is fitted into the fitting hole portion of the rack guide base body, the fitting projected portion is allowed to be press-fitted into the fitting hole portion even if a center line of curvature of the circular arc along the curved surface of the slide plate (hereinafter, simply called the center line in the axial direction of the slide plate) is inclined with respect to a center line of curvature of the recessed portion of the rack guide base body (hereinafter, simply called the center line in the axial direction of the recessed portion). If the slide plate is mounted in a state where the center line in the axial direction of the slide plate is inclined with respect to the center line in the axial direction of the recessed portion, that is, in a state where the slide plate is shifted in the rotational direction about the fitting projected portion from a regular state with respect to the rack guide base body, a gap is generated between the slide plate and the inner surface of the recessed portion of the rack guide base body, and there is the fear that the rack bar locally contacts the slide plate to cause abnormal wear.